How to identify the real cell phone memory card detailed tutorial
32 2021-07-27 21:45
Two days ago in the forum, inadvertently found a netizen's miserable experience: "He saw in an online store Kingston TF memory card promotion information, 16GB of 35 yuan, 32GB of 100 yuan, compared with the average market price is indeed much cheaper, and then he bought one of each. However, he also had doubts about such a cheap memory card, so the first time after purchase, he checked the security code on the memory card package through Kingston's official website and verified that it was indeed authentic. But after using it for a while he found that his memory card read and write speed was much slower than others and would prompt errors when copying larger files, then he downloaded a memory card testing tool from the internet and the final test results showed that the actual capacity of both memory cards was only 2GB."
Perhaps people will be puzzled, how can a 2GB memory card become 16GB and 32GB? In fact, the memory card he bought is called "expansion card", which has long been no secret within the industry and is the most common means of profit for cottage manufacturers and crooks. Generally speaking, with a dozen or twenty dollars of 2GB memory card expansion into 16GB or 32GB, and then at a low price to attract consumers to buy, where the profit has doubled several times. In response to this situation, today Xiaoyu will popularize the basics of memory cards for you, and then teach you a few simple identification methods to avoid being duped when buying.
Memory cards of the past and present life
The first thing you need to do is to get a good idea of what you are looking for. Although there were mobile games at that time, but most of them were a few dozen KB, and did not need much storage space. But with the diversification of cell phone functions, especially the addition of music, photography and video elements, the original abundant memory has become tight, some cell phones have chosen to expand the body memory, but most cell phone manufacturers still choose the memory card to expand the space of the way.
MMC memory card
Although we all use them every day, the early cell phone memory cards were not the "petite" shape they are now, and the capacity was not that large. The MMC memory card is one of the earlier ones, which was developed by Siemens and SanDisk in 1997, based on Toshiba's NAND flash memory technology, which is smaller than the CF card with Intel NOR flash memory technology. At the beginning, MMC cards were widely used, digital cameras, PDAs and cell phones could be used, with Nokia adopting relatively more models of MMC memory cards.
SD memory card
SD memory cards are a new generation of storage devices based on semiconductor flash memory, which are widely used in portable devices and have high memory capacity, fast data transfer rate, great mobile flexibility and good security. Although SD memory cards quickly took the place of MMC memory cards and have been in use ever since, they are actually based on the MMC format and the two still have some compatibility on some devices.
TF memory card
The above picture is the most common TF memory card now, it is developed by SanDisk, mainly used for mobile devices, compared to the early MMC memory card it is smaller, larger capacity, and strong compatibility. It can be converted to SD card through the card tray, which is highly expandable. In 2004, it was officially renamed as Micro SD by SD Association.
2GB to 32GB expansion card insider exposure
At the beginning of the article Xiaoyu has mentioned that the market now sells many TF memory cards, the actual storage space and the nominal does not match, like 2GB into 32GB, 4GB into 32GB situation abound. The so-called expansion card is to expand the capacity of electronic devices storage media, such as cell phones, MP3, MP4, digital cameras, U disk, CF memory cards, SD memory cards, TF memory cards, etc., these can be expanded. Especially now the most commonly used TF memory cards, the most serious expansion phenomenon, mainly concentrated in Kingston, SanDisk, the two brands.
Master chip detection tool
The above figure is a tool used to detect the master control chip of the storage device, in a 32GB expansion card on the card reader, and then connected to the computer, through this detection tool can be measured the authenticity of its master control chip. It is easy to see from the figure, the bottom reference product list shows the results: this USB flash drive may be a cottage black disk (because connected through the card reader, so the detection tool will identify it as a USB flash drive). This is because simply checking the properties or formatting the memory card without using the tool will not detect the problem, and the value displayed on the computer will remain the same after expansion. Of course, this is only a preliminary test, so if you have any doubts, you can use this method to check it first, but whether it is expanded and what the actual capacity is, you need other software to identify it.
The actual capacity of the 32GB expansion card after recovery
In fact, for consumers who buy expansion cards, the loss of money is a small matter, after all, the memory card is at most more than 200 yuan, while its greatest harm is in data security. Generally speaking, the expansion card will show an error message when copying some files, because the expanded space is not really memory. Of course, it takes certain conditions to report errors, which is the reason why many friends have not found any problems for a long time after they bought the expansion card.
File transfer process
For example, if a 2GB memory card is expanded to 32GB, when we connect it to the computer, we will not find any problem through the properties. If we copy 1000 songs with a total capacity of 3GB, the memory card will generally not behave differently and the chances of error reporting are relatively small because the size of each song is only a few MB. The data cannot be transferred. Although copying 1000 songs rarely results in an error message, the expansion part is not stable and data loss can easily occur. At the same time, the expansion will cause the memory card's service life to be reduced or even burned outright, and eventually even formatting will not be possible, and the capacity will only be shown as 8MB or 16MB, and it will not be opened. There is also a situation where a file is copied in and opened at the time with no problems, but as soon as the computer is replaced or rebooted, data is lost or errors are reported, because the system will give priority to reading the cache files on the local disk. This shows the seriousness of the danger of the expansion card, if the card files are very important, once lost will be very difficult to retrieve.
SanDisk also officially produces expansion cards?
When you see the title, you will surely be confused, how can SanDisk officially produce expansion cards? In fact, this "expansion card" is not the other expansion card, which involves a storage unit chip problem. Generally speaking, Nand flash memory is mainly divided into three categories: MLC multi-layer storage cell, SLC single-layer storage cell and TLC, and these three categories are also applicable to different usage environments, the most common is MLC and SLC, SanDisk uses MLC.
MLC Multi-Level Storage Cell
MLC is the abbreviation of Multi-Level Cell, the biggest feature of MLC is the large capacity and low cost, but the speed is very slow. In other words, the same 100 cells, MLC is much larger than the capacity of SLC, usually the manufacture of 128MB memory cards need to use 1024 units of wafer particles, while SanDisk to manufacture the same memory card only need to use 512 units of wafer particles, which is actually equivalent to the "expansion" in disguise. This is actually the equivalent of "expansion" in disguise. Although this can reduce costs, but at the expense of speed, due to the excessive data stored in each MLC memory cell, the structure is relatively complex, the chance of error is also relatively increased, must be corrected for errors, while the MLC erase life is only 5000-10000 times. Many consumers are unaware of this, and SanDisk's high visibility has masked the "flaws" in its products.
SLC single layer storage cell
SLC is an acronym for Single Layer Cell, which is characterized by stability, speed, and low power consumption, but is half the capacity and relatively high cost compared to MLC, which is 1 bit per cell and stores less data in the storage cell, making the structure relatively simple and reducing the chance of errors. Moreover, SLC flash memory can be rewritten up to 100,000 times, which is 10-20 times higher than MLC, and it is often used in enterprise SSDs, but also the cost of SLC is more than three times higher than MLC.